TY - JOUR
T1 - Reaction OH + OH studied over the 298-834 K temperature and 1 - 100 bar pressure ranges
AU - Sangwan, Manuvesh
AU - Chesnokov, Evgeni N.
AU - Krasnoperov, Lev N.
PY - 2012/6/21
Y1 - 2012/6/21
N2 - Self-reaction of hydroxyl radicals, OH + OH → H 2O + O (1a) and OH + OH → H 2O 2 (1b), was studied using pulsed laser photolysis coupled to transient UV-vis absorption spectroscopy over the 298-834 K temperature and 1-100 bar pressure ranges (bath gas He). A heatable high-pressure flow reactor was employed. Hydroxyl radicals were prepared using reaction of electronically excited oxygen atoms, O( 1D), produced in photolysis of N 2O at 193 nm, with H 2O. The temporal behavior of OH radicals was monitored via transient absorption of light from a dc discharge in H 2O/Ar low-pressure resonance lamp at ca. 308 nm. The absolute intensity of the photolysis light was determined by accurate in situ actinometry based on the ozone formation in the presence of molecular oxygen. The results of this study combined with the literature data indicate that the rate constant of reaction 1a, associated with the pressure independent component, decreases with temperature within the temperature range 298-414 K and increases above 555 K. The pressure dependent rate constant for (1b) was parametrized using the Troe expression as k 1b,inf = (2.4 ± 0.6) × 10 -11(T/300) -0.5 cm 3 molecule -1 s -1, k 1b,0 = [He] (9.0 ± 2.2) × 10 -31(T/300) -3.5±0.5 cm 3 molecule -1 s -1, F c = 0.37.
AB - Self-reaction of hydroxyl radicals, OH + OH → H 2O + O (1a) and OH + OH → H 2O 2 (1b), was studied using pulsed laser photolysis coupled to transient UV-vis absorption spectroscopy over the 298-834 K temperature and 1-100 bar pressure ranges (bath gas He). A heatable high-pressure flow reactor was employed. Hydroxyl radicals were prepared using reaction of electronically excited oxygen atoms, O( 1D), produced in photolysis of N 2O at 193 nm, with H 2O. The temporal behavior of OH radicals was monitored via transient absorption of light from a dc discharge in H 2O/Ar low-pressure resonance lamp at ca. 308 nm. The absolute intensity of the photolysis light was determined by accurate in situ actinometry based on the ozone formation in the presence of molecular oxygen. The results of this study combined with the literature data indicate that the rate constant of reaction 1a, associated with the pressure independent component, decreases with temperature within the temperature range 298-414 K and increases above 555 K. The pressure dependent rate constant for (1b) was parametrized using the Troe expression as k 1b,inf = (2.4 ± 0.6) × 10 -11(T/300) -0.5 cm 3 molecule -1 s -1, k 1b,0 = [He] (9.0 ± 2.2) × 10 -31(T/300) -3.5±0.5 cm 3 molecule -1 s -1, F c = 0.37.
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U2 - 10.1021/jp211805v
DO - 10.1021/jp211805v
M3 - Article
C2 - 22397582
AN - SCOPUS:84862700297
SN - 1089-5639
VL - 116
SP - 6282
EP - 6294
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 24
ER -